Aerogel (also called 'frozen smoke' because of its hazy blue appearance), is a truly remarkable material.
It is the lightest and lowest-density solid known to exist, and holds an unbelievable 15 entries in the Guinness Book of World Records, including best insulator and lowest density solid.
Aerogel is composed of 99.8% air and is chemically similar to ordinary glass.

Being the world's lightest known solid, it weighs only three times that of air.

When handled, Aerogel feels like a very light, hard foam. Being chemically similar to glass, it also happens to shatter like glass, yet is incredibly strong structurally, and can support thousands of times its own weight. Theoretically, a block weighing less than a pound could support a weight of half a ton.
Due to its microstructure, Aerogel is a powerful desiccant, rapidly absorbing any moisture in your fingertips when held. This usually leaves some dry spots on the skin that disappear in a short time.
Aerogel's true strength is its incredible insulating properties. It negates just about any kind of
energy transfer - thermal, electrical or acoustic.
A one-inch thick Aerogel window has the same insulation value as 15 panes of glass and trapped air - which means a conventional window would have to be ten-inches thick to equal a one-inch thick Aerogel window.

Aerogel's density is just 3 milligrams per cubic centimeter.
Its melting point is 2,200 degrees F (1,200 degrees C).

A large panel of Aerogel was most recently used by NASA in the Stardust mission, which successfully collected collect comet & interstellar dust samples & returned them to Earth. Previously, it was used in the Mars Pathfinder Rover to insulate its components from the large temperature swings on Mars.